Micropump

ABSTRACT

A method of pumping a fluid including providing a pump including a disposable component and a reusable component; connecting the disposable component and the reusable component; receiving a fluid medium from a fluid medium source into a first disposable conduit; drawing the fluid medium into a disposable piston pump assembly of a first disposable conduit; flowing the fluid medium through a disposable flow meter; measuring a flow rate of the fluid medium; discharging the fluid medium into a reusable bubble detector; and discharging the fluid medium from the reusable bubble detector if less than a preselected amount of gas is detected.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 17/011,749 filed on Sep. 3, 2020, now U.S. Pat. No. 11,779,699issuing on Oct. 10, 2023, which claims priority to U.S. ProvisionalApplication Ser. No. 62/895,575, filed Sep. 4, 2019, the entire contentsof which are incorporated herein by reference.

STATEMENT OF FEDERALLY FUNDED RESEARCH

None.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to the field of infusion pumps.In particular, the present invention relates to an infusion pump with adisposable component and a capacity to remove gases from a fluid to beinfused.

BACKGROUND OF THE INVENTION

Infusion pumps are commonly used to infuse substances such as blood andmedications into patients. Existing infusion pumps generally requirefixed power sources. Many existing infusion pumps also require costlyand time-consuming cleaning between uses. In addition, many existinginfusion pumps lack a capacity to detect and minimize the occurrence ofgases in the fluid to be infused.

The prior art includes U.S. Pat. No. 10,384,004, to Zhu, which is saidto disclose processes for operating an infusion pump for pumping fluidthough an administration set at a constant flow rate; wherein the pumpincludes a pumping mechanism for pumping fluid and operates at a pulsefrequency, and a controller controls the pulse frequency; wherein thepump has one or more sensors configured for measuring at least onecharacteristic value relating to a status of the infusion pump; whereinthe controller is configured for causing the pumping mechanism tooperate at a first pulse frequency, and the one or more sensors measurethe characteristic value; and wherein, when the measured characteristicvalue meets a threshold value, the controller causes the pumpingmechanism to operate at a second pulse frequency different from thefirst pulse frequency.

In addition, the prior art includes U.S. Pat. No. 10,387,624, to Jedwab,et al., which is said to disclose an infusion pump having a control unitand a graphical user interface functionally connected to the controller,wherein the control unit is designed to receive at least two sensorsignals out of the following group of sensors: cassette presence sensor,door sensor, pressure sensor, air presence sensor, motor sensor, flowrate sensor, wherein the control unit is designed to detect an errorstate based on the analysis of the at least two supplied sensor signals,wherein the control unit is designed to associate a degree of severityout of at least two degrees of severities based on the processing of thesupplied sensor signals, and wherein the control unit is designed tocontrol a color of the display of the graphical user interface to bedisplayed, wherein a different color is associated with each degree ofseverity as well as with a non-error state.

SUMMARY OF THE INVENTION

In some embodiments of the disclosure, a pump is disclosed as includinga disposable component including a disposable component inlet portcoupled to a first disposable conduit in fluid communication with afluid medium source, wherein the first disposable conduit includes adisposable piston pump assembly and a disposable bubble eliminator, andthe first disposable conduit is in fluid communication with a disposablecomponent outlet port, wherein the disposable bubble eliminator is influid communication with a lumen of the first disposable conduit and isoperable to reduce a gas content of a fluid medium; wherein thedisposable piston pump assembly is operable to pump the fluid mediumfrom the disposable component inlet port, through the first disposableconduit and the disposable bubble eliminator, to the disposablecomponent outlet port; and a reusable component including a reusablemovable stage operable to compress the disposable piston pump assembly;and a reusable mechanical actuator operable to drive the movable stage.In one aspect, the disposable component further includes a first one-wayoutlet valve disposed in the first disposable conduit between the pistonassembly and the disposable bubble eliminator and operable to preventthe fluid medium from flowing from the disposable bubble eliminator tothe disposable piston pump assembly; a disposable flow meter positionedto measure a fluid flow through the first disposable conduit; and asecond one-way outlet valve disposed in the second disposable conduitbetween the disposable bubble eliminator and the disposable flow meterand operable to prevent the fluid medium from flowing from thedisposable flow meter to the disposable bubble eliminator; and thereusable component further includes a reusable reception tunnelconfigured to receive at least a portion of the first disposableconduit; a reusable inlet valve operable to close the first disposableconduit when the at least a portion of the first disposable conduit isdisposed in the reusable reception tunnel; a reusable flow meterconnector operable to connect to the disposable flow meter and to conveydata from the disposable flow meter; and a reusable bubble detector. Inanother aspect, the reusable inlet valve is a one-way valve or a pinchvalve. In another aspect, the disposable piston pump assembly includes apiston barrel including a pump chamber in fluid communication with thefirst disposable conduit; a plunger slidably disposed within the pistonbarrel below the pump chamber; a piston rod attached to the plungeropposite the pump chamber; a spring cap attached to the piston rod; anda spring disposed around an exterior of the piston barrel and attachedat an upper end of the spring to the exterior of the piston barrel andat a lower end of the spring to the spring cap, wherein the spring isdisposed to store energy when the plunger, the piston rod, and thespring cap are moved into the piston barrel and is disposed not to storeenergy when the plunger is at the lower end of the pump chamber; whereinthe reusable movable stage is disposed to move the plunger upward in thepiston barrel and the spring is disposed to move the plunger downward inthe pump chamber. In another aspect, the disposable bubble eliminator isin fluid communication with the disposable piston pump assembly and thedisposable flow meter and includes a vent through which gas in the fluidmedium may escape the disposable bubble eliminator to the atmospherewhen pressure higher than atmospheric pressure is maintained in thedisposable bubble eliminator. In another aspect, the disposablecomponent further includes a disposable position measurement device todetect an alignment of the disposable component with the reusablecomponent when assembled together. In another aspect, the reusablebubble detector includes a reusable bubble detector conduit in fluidcommunication with the disposable component outlet port when thedisposable component and the reusable component are assembled together;and a reusable ultrasonic sensor to detect gas in the fluid medium,disposed outside the reusable bubble detector conduit. In anotheraspect, the reusable component further includes an internal electricbattery or electrical connections configured to connect to an externalelectrical power source or both. In another aspect, the reusablecomponent further includes an internal power management system or powermanagement connections configured to connect to an external powermanagement system or both. In another aspect, the reusable componentfurther includes an integral control panel or control panel connectionsconfigured to connect to an external control panel or both. In anotheraspect, the reusable component further includes a screen interface orscreen interface connections configured to connect to an external screeninterface or both. In another aspect, the disposable component isenclosed in a disposable housing or the reusable component is disclosedin a reusable housing or both.

In some embodiments of the disclosure, a method of pumping a fluid isdisclosed as including providing a disposable pump component including adisposable component inlet port coupled to a first disposable conduit influid communication with a fluid medium source, wherein the firstdisposable conduit includes a disposable piston pump assembly and adisposable bubble eliminator, and the first disposable conduit is influid communication with a disposable component outlet port, wherein thedisposable bubble eliminator is in fluid communication with a lumen ofthe first disposable conduit and is operable to reduce a gas content ofa fluid medium, and wherein the disposable piston pump assembly isoperable to pump the fluid medium from the disposable component inletport, through the first disposable conduit and the disposable bubbleeliminator, to the disposable component outlet port; and connecting thedisposable component to a reusable component including a reusablemovable stage operable to compress the disposable piston pump assembly;and a reusable mechanical actuator operable to drive the movable stage.

In some embodiments of the disclosure, a method of pumping a fluidmedium is disclosed as including receiving the fluid medium from a fluidmedium source into a conduit; drawing the fluid medium into a disposablepiston pump assembly in the conduit, the conduit further including adisposable bubble eliminator operable to vent gas from the fluid mediumwithin the disposable bubble eliminator; flowing the fluid mediumthrough a disposable flow meter; measuring a flow rate of the fluidmedium; discharging the fluid medium into a reusable bubble detector;detecting residual gas in the fluid medium; if less than a preselectedamount of gas is detected, discharging the fluid medium from thereusable bubble detector. In one aspect, the disposable piston pumpassembly includes a piston barrel including a pump chamber in fluidcommunication with the first disposable conduit; a plunger slidablydisposed within the piston barrel below the pump chamber; a piston rodattached to the plunger opposite the pump chamber; a spring cap attachedto the piston rod; and a spring disposed around an exterior of thepiston barrel and attached at an upper end of the spring to the exteriorof the piston barrel and at a lower end of the spring to the spring cap,wherein the spring is disposed to store energy when the plunger, thepiston rod, and the spring cap are moved from a lower end of the pistonbarrel and is disposed not to store energy when the plunger is at thelower end of the pump chamber; wherein the reusable movable stage isdisposed to move the plunger into the pump chamber and the spring isdisposed to move the plunger out of the pump chamber. In another aspect,the disposable bubble eliminator is in fluid communication with thedisposable piston pump assembly and the disposable flow meter andincludes a vent through which gas in the fluid medium may escape thedisposable bubble eliminator to the atmosphere when pressure higher thanatmospheric pressure is maintained in the disposable bubble eliminator.In another aspect, the method further includes detecting an alignment ofthe disposable component with the reusable component when assembledtogether. In another aspect, the reusable bubble detector includes areusable bubble detector conduit in fluid communication with thedisposable component outlet port when the disposable component and thereusable component are assembled together; and a reusable ultrasonicsensor to detect gas in the fluid medium, disposed outside the reusablebubble detector conduit. In another aspect, the method further includessupplying electrical power from an internal electric battery or anexternal electrical power source. In another aspect, the method furtherincludes managing electrical power with an internal power managementsystem or an external power management system. In another aspect, themethod further includes supplying an integral screen interface or anexternal screen interface.

In some embodiments of the disclosure, a kit is disclosed as including adisposable component including a disposable component inlet port coupledto a first disposable conduit in fluid communication with a fluid mediumsource, wherein the first disposable conduit includes a disposablepiston pump assembly and a disposable bubble eliminator, and the firstdisposable conduit is in fluid communication with a disposable componentoutlet port, wherein the disposable bubble eliminator is in fluidcommunication with a lumen of the first disposable conduit and isoperable to reduce a gas content of a fluid medium; wherein thedisposable piston pump assembly is operable to pump the fluid mediumfrom the disposable component inlet port, through the first disposableconduit and the disposable bubble eliminator, to the disposablecomponent outlet port; and a reusable component including a reusablemovable stage operable to compress the disposable piston pump assembly;and a reusable mechanical actuator operable to drive the movable stage.In one aspect, the disposable component further includes a first one-wayoutlet valve disposed in the first disposable conduit between the pistonassembly and the disposable bubble eliminator and operable to preventthe fluid medium from flowing from the disposable bubble eliminator tothe disposable piston pump assembly; a second disposable conduit thatplaces the disposable bubble eliminator in fluid communication with adisposable flow meter; a second one-way outlet valve disposed in thesecond disposable conduit between the disposable bubble eliminator andthe disposable flow meter and operable to prevent the fluid medium fromflowing from the disposable flow meter to the disposable bubbleeliminator; and the reusable component further includes a reusablereception tunnel configured to receive at least a portion of the firstdisposable conduit; a reusable inlet valve operable to close the firstdisposable conduit when the at least a portion of the first disposableconduit is disposed in the reusable reception tunnel; a reusable flowmeter connector operable to connect to the disposable flow meter and toconvey data from the disposable flow meter; and a reusable bubbledetector. In another aspect, the reusable inlet valve is a one-way valveor a pinch valve. In another aspect, the disposable piston pump assemblyincludes a piston barrel including a pump chamber in fluid communicationwith the first disposable conduit; a plunger slidably disposed withinthe piston barrel below the pump chamber; a piston rod attached to theplunger opposite the pump chamber; a spring cap attached to the pistonrod; and a spring disposed around an exterior of the piston barrel andattached at an upper end of the spring to the exterior of the pistonbarrel and at a lower end of the spring to the spring cap, wherein thespring is disposed to store energy when the plunger, the piston rod, andthe spring cap are moved into the piston barrel and is disposed not tostore energy when the plunger is at the lower end of the pump chamber;wherein the reusable movable stage is disposed to move the plungerupward in the piston barrel and the spring is disposed to move theplunger downward in the pump chamber. In another aspect, the disposablebubble eliminator is in fluid communication with the disposable pistonpump assembly and the disposable flow meter and includes a vent throughwhich gas in the fluid medium may escape the disposable bubbleeliminator to the atmosphere when pressure higher than atmosphericpressure is maintained in the disposable bubble eliminator. In anotheraspect, the disposable component further includes a disposable positionmeasurement device to detect an alignment of the disposable componentwith the reusable component when assembled together. In another aspect,the reusable bubble detector includes a reusable bubble detector conduitin fluid communication with the disposable component outlet port whenthe disposable component and the reusable component are assembledtogether; and a reusable ultrasonic sensor to detect gas in the fluidmedium, disposed outside the reusable bubble detector conduit. Inanother aspect, the reusable component further includes an internalelectric battery or electrical connections configured to connect to anexternal electrical power source or both. In another aspect, thereusable component further includes an internal power management systemor power management connections configured to connect to an externalpower management system or both. In another aspect, the reusablecomponent further includes an integral control panel or control panelconnections configured to connect to an external control panel or both.In another aspect, the reusable component further includes a screeninterface or screen interface connections configured to connect to anexternal screen interface or both. In another aspect, the disposablecomponent is enclosed in a disposable housing or the reusable componentis disclosed in a reusable housing or both.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent invention, reference is now made to the detailed description ofthe invention along with the accompanying figures, in which:

FIG. 1 shows the disposable component and the reusable component of thepump attached together.

FIG. 2 shows the disposable component and the reusable component of thepump detached from each other.

FIG. 3 shows the disposable pump assembly.

FIGS. 4A-4E show the arrangement of the disposable pump assembly at thecompletion of the pump stroke, mid-way through the refill stroke, at thecompletion of the refill stroke, mid-way through the pump stroke, and atthe return to the completion of the pump stroke, respectively.

FIGS. 5A, 5B, and 5C show the relative positions of the disposable pumpassembly and the reusable movable stage during connection of thedisposable component and the reusable component, when the disposablecomponent and the reusable component are attached, and during detachmentof the disposable component and the reusable component, respectively.

FIGS. 6A and 6B show the disposable bubble eliminator during the pumpstroke of the disposable pump assembly and during the refill stroke ofthe disposable pump assembly, respectively.

FIGS. 7A and 7B show the bubble eliminator chamber and the approximatefluid flow lines within it, respectively. FIGS. 7C-7G show thedisposable bubble eliminator effectively performing, with a bubbleprogressively becoming smaller as the bubble's air passes out throughthe ePTFE membrane.

FIGS. 8A-8K show results of a study to investigate various bubbleventing specifications, Examples 1-11.

FIGS. 9A-9D schematically depict Examples 12-15, representing additionalconfigurations tested.

FIG. 10 shows a flowchart for a method embodiment of the presentinvention.

FIG. 11 shows a flowchart for another method embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Illustrative embodiments of the system of the present application aredescribed below. In the interest of clarity, not all features of anactual implementation are described in this specification. It will ofcourse be appreciated that in the development of any such actualembodiment, numerous implementation-specific decisions must be made toachieve the developer's specific goals, such as compliance withsystem-related and business-related constraints, which will vary fromone implementation to another. Moreover, it will be appreciated thatsuch a development effort might be complex and time-consuming but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure.

In the specification, reference may be made to the spatial relationshipsbetween various components and to the spatial orientation of variousaspects of components as the devices are depicted in the attacheddrawings. However, as will be recognized by those skilled in the artafter a complete reading of the present application, the devices,members, apparatuses, etc. described herein may be positioned in anydesired orientation. Thus, the use of terms such as “above,” “below,”“upper,” “lower,” or other like terms to describe a spatial relationshipbetween various components or to describe the spatial orientation ofaspects of such components should be understood to describe a relativerelationship between the components or a spatial orientation of aspectsof such components, respectively, as the device described herein may beoriented in any desired direction.

Infusion pumps are commonly used to infuse substances such as blood andmedications into patients. They often need to be used untethered fromelectrical power connections, such as in ambulatory situations, whereoperation by internal battery power is convenient or necessary. Also, itis desirable to have a pump comprising certain disposable componentswhich, for patient safety reasons, are discarded and replacedfrequently. It is desirable that a pump have the operability to detectand minimize occurrence of gases in the fluid to be infused, to ensurecorrect direction of fluid flow, to prevent uncontrolled flow of fluidto be infused, and to control the rate of flow of fluid that is beinginfused, with accurate measurement and verification of the rate of fluidflow.

An embodiment of the present invention, a pump 100 for achievingcontrollable flow, is depicted in FIG. 1 . The invention includes afluid flow path that is defined by multiple disposable parts andsystems. The disposable fluid flow path comes into contact with fluids,such as intravenous delivery fluids, drug solutions, blood products, andsolutions of bioactive agents. The disposable parts are housed by adisposable component 101.

The invention includes reusable parts and systems that do not come intocontact with fluids. The reusable parts and systems are durable andfunction multiple times with a plurality of different disposablecomponents. In one embodiment, the reusable parts and systems are housedby a reusable component 102. In some embodiments, the parts used toachieve conversion of electrical energy, e.g., electrical energy storedin a battery 128, to mechanical action are housed by the reusablecomponent 102, as are various mechanical drivers, the equipment formonitoring system performance and, the control panel 132 and the edittouch screen 134 for interfacing with a user. The controls to controlaction and speed motion of the pump are located on the reusablecomponent. It would be wasteful and costly to dispose of these reusableparts because of their sophistication and complexity.

The invention is intended to meet the requirements that a new disposablecomponent 101 be easily connected to and removed from the reusablecomponent 102 and that the disposable and reusable components 101 and102 respectively, achieve physical, mechanical and electricalintegration when attached to each other.

FIG. 1 depicts an embodiment of the present invention, the pump 100,including a disposable component 101 and a reusable component 102, whichare shown attached together. The disposable component 101 includes adisposable component inlet port 104 coupled to a first disposableconduit 106 in fluid communication with a fluid medium source (notshown). The first disposable conduit 106 is in fluid communication witha disposable piston pump assembly 140 and a disposable bubble eliminator160 with bubble eliminator chamber 162. The first disposable conduit 106is in fluid communication with a disposable component outlet port 180.The disposable bubble eliminator 160 is in fluid communication with alumen (not shown) of the first disposable conduit 106, and is operableto reduce a gas content of a fluid medium. The disposable piston pumpassembly 140 is operable to pump the fluid medium from the disposablecomponent inlet port 104, through the first disposable conduit 106 andthe disposable bubble eliminator 160, to the disposable component outletport 180. The reusable component 102 includes a reusable movable stage108 operable to compress the disposable piston pump assembly 140 and areusable mechanical actuator 110 operable to drive the reusable movablestage 108.

The disposable component 101 may further include a second disposableconduit 112 in fluid communication with the disposable bubble eliminator160 and the disposable component outlet port 180. The disposablecomponent 101 may also include a first one-way outlet valve 114 disposedin the first disposable conduit 106 between the disposable piston pumpassembly 140 and the disposable bubble eliminator 160, and operable toprevent the fluid medium from flowing from the disposable bubbleeliminator 160 to the disposable piston pump assembly 140. Thedisposable component 101 may further include a disposable flow meter 116disposed to measure fluid flow through the second disposable conduit112. The disposable component 101 may also include a second one-wayoutlet valve 118 disposed between the disposable bubble eliminator 160and the disposable flow meter 116 and operable to prevent the fluidmedium from flowing from the disposable flow meter 116 to the disposablebubble eliminator 160.

The reusable component 102 may further include a reusable receptiontunnel 120 configured to receive at least a portion of the firstdisposable conduit 106. The reusable component 102 may also include areusable inlet valve 122 that is operable to close the first disposableconduit 106 when the at least a portion of the first disposable conduit106 is disposed in the reusable reception tunnel 120. The reusablecomponent 102 may also include a reusable flow meter connector 124operable to connect to the disposable flow meter 116 and to convey datafrom the disposable flow meter 116. The reusable component 102 mayfurther include a reusable bubble detector 126. The reusable component102 may also include an internal electric battery or electricalconnections configured to connect to an external electrical power source128 or both. The reusable component 102 may also include an internalpower management system or power management connections configured toconnect to an external power management system 130 or both. The reusablecomponent 102 may also include an integral control panel or controlpanel connections configured to connect to an external control panel 132or both. The reusable component 102 may also include a screen interfaceor screen interface connections configured to connect to an externalscreen interface 134 or both.

FIG. 1 depicts the operational configuration of one embodiment of thepump 100, where the reusable component 102 is coupled, physically,mechanically, and electrically to the disposable component 101. FIG. 2depicts the situation when the disposable and reusable components shownattached in FIG. 1 are disconnected from each other.

The disposable component 101 includes the reciprocating disposablepiston pump assembly 140, which is of metallic or polymer construction.The disposable piston pump assembly 140 makes contact with a moveablestage 108 in the reusable component 102. The motion of the reusablemoveable stage 108 is driven by the mechanical actuator 110, which isalso in the reusable component 102. The reusable mechanical actuator 110provides the driving force for the forward stroke of the disposablepiston pump assembly 140. The parts needed for converting electricalenergy stored in the batteries 128 into mechanical actuation are housedin the reusable component 102, since the parts needed forelectrical-to-mechanical conversion typically have significantelectrical and mechanical complexity.

In the embodiment shown in FIGS. 1 and 2 , the fluid path is defined bytubing and valves, consisting of a disposable component inlet port 104,a disposable component outlet port 180, and a piston pump chamber 144.The fluid flow path is defined by tubing and connections of the typeused for delivery of intravenous fluids to the body. The parts definingthe fluid path are housed in the disposable component 101. Thedisposable component 101 includes a disposable component inlet port 104for receiving the fluid and a disposable component outlet port 180 forsupplying the fluid to a patient. A controllable disposable piston pumpassembly 140, incorporating the piston pump chamber 144, is used forfluid flow from the disposable component inlet port 104 to the outletport 180. The reusable inlet valve 122 is disposed in proximity to thedisposable component inlet port 104. The reusable inlet valve 122 opensand closes the first disposable conduit 106, which may be disposable IVtubing. In the embodiment illustrated, the reusable inlet valve 122uses, e.g., a pinch valve mechanism. A pinch valve is a component thatallows the mechanical pinching of the outside of a tube, wheremechanical pressure deforms the tube sufficiently to restrict or stopflow through the tube's internal diameter. Flow resumes when themechanical pressure to the outside of the tube is released. The benefitof a pinch valve, compared to alternatives such as a solenoid valve, isthat the valve's parts and mechanisms do not come in contact with fluid.A pinch valve can be physically mounted, in its entirety, in thereusable component 102, so as not to dispose of it after a single use.The fluid path through the reusable inlet valve is therefore defined byplacement of the first disposable conduit 106.

The controllable disposable piston pump assembly 140 is disposed andoperated to achieve fluid flow in the direction of the disposablecomponent outlet port 180. In addition to the reusable inlet valve 122and the disposable piston pump assembly 140, there are two one-wayoutlet valves (V1 and V2), 114 and 118, respectively, disposed betweenthe disposable piston pump assembly and the disposable component outletport. The one-way outlet valves V1 114 and V2 118 are part of thedisposable component 101. The fluid is pumped in only one directionbecause the one-way outlet valves V1 114 and V2 118 are normally closedbut open in response to fluid pressure. In the embodiment shown in FIG.1 , after fluid is introduced into the pump chamber 144, the reusableinlet valve 122 is closed. As the piston increases the pressure in thepump chamber 144, the output valves V1 114 and V2 118 downstream areforced open, and the fluid flows towards the disposable component outletport 180. When the pressure drops sufficiently during the retractionstroke, the one-way outlet valves V1 114 and V2 118 close, and thereusable inlet valve 122 is opened to admit more fluid. The two one-wayoutlet valves V1 114 and V2 118 are passive (not controlled electricallyas compared to the inlet valve 122). These valves V1 114 and V2 118 areumbrella-type valves, allowing fluid to flow one direction but not theother. An umbrella valve looks like an umbrella. As the fluid travels inone direction the umbrella valve opens allowing the fluid to pass, butas the fluid tries to reverse direction, the umbrella valve closes andprevents any fluid from traveling towards the inlet.

The embodiment shown in FIGS. 1 and 2 includes a disposable bubbleeliminator 160 located between one-way outlet valves V1 114 and V2 118.The disposable bubble eliminator 160 includes a fluid chamber 162. Oneor more walls of the chamber 162 are formed from a gas permeable porousmembrane 164, allowing gas to vent to the external atmosphere. Thedisposable bubble eliminator 160 is placed in the fluid flow path suchthat positive pressure conditions are maintained within the bubbleeliminator chamber 162 at all times. Operation and orientation ofone-way valves V1 114 and V2 118 working in coordination with thedisposable piston pump assembly 140, are important in managing thebubble eliminator chamber 162 fluid pressure. The fluid side of thedisposable bubble eliminator 160 is always is at a higher pressure thanatmospheric during the prime stroke as well as the forward stroke of thedisposable piston pump assembly 140.

The embodiment shown in FIGS. 1 and 2 includes the disposable flow meter116 positioned towards the outlet. The device is suitable for monitoringor measuring the activity and accuracy of the disposable piston pumpassembly 140. The disposable flow meter 116 is part of the disposablecomponent 101. An example disposable flow meter is the Sensiron LD20-2600B. It operates based on a thermal gradient detection, suitablefor integration into the disposable component 101. The disposable flowmeter 116 is a direct flow measurement device used to monitor gross flowrate error, occlusion, and infiltration and to verify that the pump headis installed properly. The disposable flow meter 116 can measure theflow of all standard IV fluids, drugs formations, as well as blood andother high viscosity fluids. The flow meter may also assist in a freeflow prevention algorithm.

In the embodiment shown in FIGS. 1 and 2 the disposable flow meter 116has the additional purpose of determining correct positioning of thedisposable component 101 with respect to the position of the reusablecomponent 102. This informs the user that correct alignment between thecomponents 101 and 102 is achieved, to accomplish physical, mechanical,and electrical coupling prior to pump operation. The flow sensoroperates in conjunction with a reusable flow meter connector 124, whichis part of the reusable component 102.

The embodiment shown in FIGS. 1 and 2 incorporates a reusable bubbledetector 126, which may include an ultrasonic sensor, to detectair-in-line scenarios. Critical to the safety of the patient during adrug, IV fluid, or blood component infusion is the detection of airboluses in the tubing. An example reusable ultrasonic sensor is a MoogLifeGuard Air Bubble Detector. This reusable ultrasonic sensor is anon-wetted component. It uses ultrasonic frequencies to measure thefluid response in the tubing, alerting the operator if bubbles 50-100 uLare present. The sensor is a part of the reusable component 102.

For fluid flow metering, another method is to measure the movement ofthe piston of the disposable piston pump assembly 140 very accuratelyand, with electronic feedback control, use that movement to measure thevolume of fluid pumped. The timing of the reusable inlet valve 122 andthe reusable mechanical actuator 110 thus can be precisely adjusted toprovide accurate fluid flow. The one-way outlet valves V1 114 and V2 118deflection information, available through a transducer, may provideinformation which is substantially representative of the operationalstate of the disposable piston pump assembly 140, thereby enablingcontrol of the timing. In addition to control of timing, the outlet flowfrom the piston valve may include a device that allows detection ofocclusion or partial occlusion of outflow from the pump, gas trapped inthe disposable piston pump assembly 140, mechanical failure,disconnection of the line to the patient, and exhaustion of fluidsupply.

The disposable fluid lines may be packaged with the disposable component101 in order for ease of installment and replacement. The disposablecomponent 101 connects to the reusable component 102 by single actionclips (not shown) to minimize effort of swapping pump heads. The fluidlines will also be compatible with standard IV drugs, as well as blood,plasma, water, etc.

To operate the pump 100, a user interacts with the touch screen 134. Thetouch screen 134 may give access to a drug library with preset settingsthat will include flow rates, bolus amounts for a given patients weightfor the various drugs. The user has the capability to manually input theflow rate as well as volume in order for custom solutions. The systemalso has the capability to be continually updated to include or removedrugs and the parameters associated with them.

The packaging of the pump will house all the components within either ofthe disposable or reusable components, 101 or 102, respectively. Thepump parts may have labels and markings permanently displayed consistentwith regulatory agency labeling requirements. It may also have thenecessary visual and audible alarms and indicators according to the IECstandard for medical pumps indicating various states (end of infusion,occlusion, air-in-line, battery, equipment failure, etc.). The pump 100has the capability to be controlled and monitored via Wi-Fi/Bluetooth aswell as ability to turn off those features for security purposes.

The control board 132 for the pump may contain a processor in order tooperate all electrical components. The reusable component 102 may alsocontain a Power Management System (PMS) 130 voltage balancing andmonitoring, H bridges for reversing the polarity of voltage sourceelectrically coupled to the circuitry of the pump actuation mechanism,sensors for component monitoring, and various other electricalcomponents to operate the pump. The control board 132 also has thecapability of controlling the magnitude of voltage or current applied tothe individual actuators.

Pumping Mechanism. In the embodiment shown in FIGS. 1 and 2 , the partsof the pump that contact the fluids that form the fluid flow path arelocated on the disposable component 101, including the disposable pistonpump assembly 140, shown in detail in FIG. 3 . The reusable piston pumpassembly 140 includes a piston barrel 142 that includes the pump chamber144 in fluid communication with the first disposable conduit 106, aplunger 146 slidably disposed within the piston barrel 142 below thepump chamber 144, a piston rod 148 attached to the plunger 146 oppositethe pump chamber 144, and a spring cap 150 attached to the piston rod148. Further, the reusable piston pump assembly 140 includes a spring152 disposed around an exterior of the piston barrel 142 and attached atan upper end of the spring 152 to the exterior of the piston barrel 142and at a lower end of the spring 152 to the spring cap 150. The spring152 is disposed to store energy when the plunger 146, the piston rod148, and the spring cap 150 are moved into the piston barrel 142 and isdisposed not to store energy when the plunger 146 is at the lower end ofthe pump chamber 144. FIG. 3 illustrates disposable piston pump assembly140 with the spring 152 in a compressed, energy-storing state and theplunger 146 moved into the piston barrel 142. The disposable piston pumpassembly 140 may also include a dead volume spacer 154 disposed on theplunger 146 in the pump chamber 144, a plunger insert 156 disposedinside the plunger 144, and a piston hardstop 158 disposed at the bottomof the piston barrel 142.

The disposable piston pump assembly 140 has a flow channel in fluidcommunication with the disposable component inlet port 104 and thedisposable component outlet port 180 via the first disposable conduit106. One end of the spring 152 is permanently affixed to the disposablepiston pump assembly 140 through a permanent attachment mechanism, suchas a grooved recess, a weld, solder or adhesive. The opposite end of thespring 152 is permanently connected to the spring cap 150. The permanentattachment of spring 152 to one end of the spring cap 150 is made via agrooved recess, or alternatively by a weld, solder or adhesive. Themovement of the plunger 146 is constrained in the forward direction bythe piston pump chamber wall at the outlet side. The plunger 146 isconstrained in the retracted position by a piston hardstop 158.

Forward movement of the plunger 146 occurs until it reaches a stoppoint. The disposable piston pump assembly's 140 forward stroke resultsin the delivery of media from the piston chamber 144. Return orretraction of the plunger 146 occurs under the force of a spring 152,causing the pressure in the piston chamber 144 to fall. The reducedpressure in the piston chamber 144 causes media to flow from the inletportion 104 through an opening in the piston chamber to refill thepiston chamber 144, thus equalizing the pressure between the fluidsource and the piston chamber 144. This can be referred to as theretraction, refill, or prime stroke, which prepares the disposablepiston pump assembly 140 for its next forward or delivery stroke.

FIGS. 4A-4E show how fluid transfer from the disposable component inletport 104 to the disposable component outlet port 180 is achieved,involving sequential and coordinated actions involving parts of thedisposable component 101 and parts of the reusable component 102. FIGS.4A-4E depict disposable piston pump assembly 140 including the pumpchamber 144, the plunger 146, the spring cap 150, the spring 152, and,in addition, the first disposable conduit 108, the reusable movablestage 108, and the reusable inlet valve 122.

FIG. 4A shows the arrangement of the disposable piston pump assembly 140at the completion of the forward or pump stroke. The plunger 146 is inthe fully forward position. The pump chamber 144 is substantially emptyof fluid. The spring 152 is compressed from its resting position. Thereusable inlet valve 122 on the first disposable conduit 106 is closed.There is no more fluid flow in the direction of the disposable componentoutlet port 180. The reusable mechanical actuator 110 of the movablestage is disengaged.

FIG. 4B shows the arrangement mid-way during the retraction or refillstroke of the disposable piston pump assembly 140, where the plunger 146is partially retracted. During the retraction stroke, the spring 152undergoes extension which applies a force to the spring cap 150. Themechanical force of the spring 152 acting on the spring cap 150 causesretraction of the plunger 146. Retraction of the plunger 146 results innegative pressure (less than atmospheric) within the pump chamber 144.Fluid flows into the pump chamber 144 from the outlet, due to negativechamber pressure. The refill stroke coincides with mechanical activationto open the reusable inlet valve 122. Due to negative pressure in thepump chamber, one-way outlet valves V1 114 and V2 118 (not shown) areclosed, so as to prevent or restrict flow in the direction of thedisposable component outlet port 180 (not shown). In addition to theextension of the spring 152 providing force for plunger 146 retraction,the extension of the spring 152 also applies force to the reusablemovable stage 108 causing its retraction. The force to retract thereusable movable stage 108 is applied via the spring cap 150, whichmakes physical contact with the reusable movable stage 108 via a contactsurface. During the retraction stroke, the mechanical actuator connectedto the reusable movable stage 108 is disengaged, so the reusable movablestage 108 is free to move in the retraction direction. Thus, during therefill stroke, the disposable component 101 has an energy transferfunction, where mechanical energy stored in the spring 152 istransferred to the reusable movable stage 108, which is part of reusablecomponent 102.

FIG. 4C shows the disposable piston pump assembly 140 configuration atthe completion of the retraction or refill stroke. The plunger 146 isfully retracted. The disposable piston pump assembly is primed, wherethe spring cap 150 and the plunger 146 have moved to a stop position andthe reusable movable stage has returned to a hard stop position. Thereusable inlet valve is open but there is no flow into the pump chamberdue to pressure equalization between the pump chamber and the externalfluid source. One-way outlet valves V1 114 and V2 118 are closed. Thereusable mechanical actuator 110 (not shown) which drives the reusablemovable stage is disengaged.

FIG. 4D shows an arrangement at a mid-point of the forward or pumpstroke. The force for the forward stroke comes from activating thereusable movable stage 108. During the forward stroke, the reusablemechanical actuator 110 is engaged, moving the reusable movable stage108 in the forward direction. At the same time, contact is made againstthe spring cap 150, and the forward motion of the reusable movable stage108 pushes against the spring cap 150, moving the plunger 146 forward.Forward motion of the reusable movable stage also acts on the spring cap150 to cause compression of the spring 152. Activation of the forwardstroke coincides with mechanical action to close the reusable inletvalve. The increased pressure in the pump chamber during the forwardstroke causes fluid to exit the pump chamber under pressure (greaterthan atmospheric). The increased pressure of the fluid causes one-wayoutlet valves V1 114 and V2 118 (not shown) from closed positions toopen positions. During the pump stroke, the reusable component 102 has adual energy transfer function. Mechanical force exerted by the reusablemovable stage 108 is transferred to the disposable component 101 to movethe plunger 146 and increase fluid pressure. Also, mechanical forceexerted by the reusable movable stage 108 is transferred to thedisposable component 101 to compress the spring 152, which storesmechanical energy until the refill stroke.

At the completion of the forward stroke the plunger 146 is in theforward position. The pump chamber 144 is substantially empty of fluid.The spring 152 is compressed from its resting position. Mechanicalenergy is stored in the spring 152. This situation is as depicted inFIG. 4E, which duplicates FIG. 4A. The sequence depicted in FIGS. 4A-4Erepeats itself until the desired volume of fluid is infused. Thesequence is driven at a frequency corresponding to the desired rate setby the user.

To summarize, mechanical energy transfer events needed to achieve thepumping actions of the disposable piston pump assembly 140 are sharedbetween the reusable and disposable components, 102 and 101,respectively. During the pump stroke, forward motion of the reusablemechanical actuator 110 transfers energy to the disposable component 101to move the plunger 146 and compress the spring 152. Mechanical energystored by the disposable component 101 is released during the retractionstroke, to retract the plunger 146 and reposition the reusable movablestage 108.

The disposable piston pump assembly 140 operates entirely withoutattachment mechanism or linking device between the reusable movablestage 108 and the spring cap 150 of the disposable piston pump assembly140. Movement in the forward direction is achieved by applying a forcefrom the reusable component 102 via a contact surface only. Similarly,movement in the retraction direction is achieved by applying a forcefrom the disposable component 101 via contact surfaces only. As shown inFIGS. 5A, 5B, and 5C, this arrangement allows easy and rapid insertionof the disposable component 101, since there is no mechanical connectionor disconnection step required to couple together the spring cap 150 andthe reusable movable stage 108. FIG. 5A shows the disposable piston pumpassembly 140 being brought into contact with the reusable movable stage108 as the disposable component 101 (not shown) is attached to thereusable component 102 (not shown). FIG. 5B shows the disposable pistonpump assembly 140 in contact with the reusable movable stage 108 whenthe disposable component 101 (not shown) and the reusable component 102(not shown) are attached together. FIG. 5C shows the disposable pistonpump assembly 140 being removed from contact with the reusable movablestage 108 as the disposable component 101 (not shown) is detached fromthe reusable component 102 (not shown).

Disposable Bubble Eliminator. FIGS. 6A and 6B show the disposable bubbleeliminator 160 during the pump stroke of the disposable piston pumpassembly 140 and during the refill stroke of the disposable piston pumpassembly 140, respectively. FIGS. 6A and 6B show the disposable bubbleeliminator 160, which includes a bubble eliminator chamber 162 in fluidcommunication with the first disposable conduit 106 and the seconddisposable conduit 112; a porous membrane 164 disposed as a wall of thebubble eliminator chamber 162 and in fluid communication with theatmosphere; and a mesh backing 166 disposed on an exterior surface ofthe porous membrane 164. The disposable bubble eliminator 160 may alsoinclude one or more flow spacers 168.

The disposable bubble eliminator 160 is used to prevent or minimize therisk of injury to the patient from air embolism during delivery offluids to the body. Dissolved gasses within the delivered fluid can formbubbles out of solution due to pressure changes, temperature changes,flow irregularities, or other factors. A need exists for a device thatremoves gas bubbles and/or dissolved gas from fluids delivered to apatient via the intravenous route during a medical procedure. A needalso exists for such a device that can be located at a point in thefluid delivery line near the patient, to minimize the potential forbubble formation between the device and the patient. The presentinvention includes a gas elimination device meeting these and otherneeds. The disposable bubble eliminator 160 uses the porous membrane 164in contact with a fluid. Gas passes from the fluid and into thesurrounding atmosphere due to a pressure differential. The disposablebubble eliminator 160, with associated one-way valves V1 114 and V2 118(shown in FIGS. 6A and 6B), is designed to match the mechanics of thedisposable piston pump assembly 140 and achieves coordination with theaction of the disposable piston pump assembly 140 in a specific way. Thedisposable bubble eliminator 160 of an embodiment of the presentinvention is capable of exactly managing the pressure of the fluidpresent inside the bubble eliminator chamber 162 as the disposablepiston pump assembly 140 alternates between forward and priming strokes.Management of the pressure of the fluid within the bubble eliminatorchamber 162 is essential for proper function of the disposable bubbleeliminator 160 and avoids disposable piston pump assembly 140 failure.

Coordinated Action with the Disposable Piston Pump Assembly 140. FIGS.6A and 6B show the disposable bubble eliminator 160 arrangement withdepiction of the fluid flow path during the forward and prime stokes ofthe disposable piston pump assembly 140. The disposable bubbleeliminator 160 shown includes the bubble eliminator chamber 162 withdimensions of 0.85 in ×1.0 in ×0.004 in and an internal volume of 0.0034in³. The porous membrane 164, which may include expandedpolytetraflouroethylene (ePTFE), forms a portion of side wall of thebubble eliminator chamber 162. The air permeability of the porousmembrane 164 can be 0.20-0.45 ft³/min/ft². The purpose of the porousmembrane 164 is to allow gas to permeate through the filter via apositive pressure differential between the two sides of the porousmembrane 164. A mesh backing 166 provides mechanical support to theporous membrane 164. The flow spacers 168 form a mechanical gas-tightseal. Representative bubbles 170 are also shown. The disposable bubbleeliminator 160 is positioned in the fluid flow path between one-wayoutlet valves V1 114 and V2 118. One-way outlet valve V1 114 is locatedat the fluid entry side of the bubble eliminator chamber 162. One-wayoutlet valve V1 114 is a silicone umbrella-type valve allowing flow inone direction and checks flow in the opposite direction. One-way outletvalve V1 114 is engineered to open under a specific cracking pressure of0.03 psig (Minivalve UM 070.004). The one-way outlet valve V2 118 islocated at the fluid exit side of the bubble eliminator chamber 162. Theone-way outlet valve V2 118 is an umbrella type with a cracking pressureof 2.4 psig (Minivalve UM 070.006). The one-way outlet valves V1 114 andV2 118 are passive: they are not controlled electrically.

FIG. 6A shows the disposable bubble eliminator 160 during the forwardstroke of the disposable piston pump assembly 140, when the reusableinlet valve 122 is closed and the pump chamber 144 is being pressurizedby the forward motion of the plunger 146. During the forward stoke,pressure in the fluid flow path between the reusable inlet valve 122 andone-way outlet valve V1 114 reaches values of 7-9 psig (pounds persquare inch gauge). Gauge pressure is a measure of the fluid pressurerelative to ambient atmospheric pressure. Fluid flow is towards thedisposable component outlet port 180. A decrease in fluid pressureoccurs across valve one-way outlet valve V1 114, resulting in a fluidpressure of 5-7 psig inside the bubble eliminator chamber 162 and in theregion of the porous membrane 164. Thus, there is a positive pressuredifferential between the bubble eliminator chamber 162 internal fluidand the external vent area, causing venting of gas from solution to theoutside through the porous membrane 164. During the forward stroke,another pressure drop occurs across one-way outlet valve V2 118, suchthat the fluid pressure in the conduit between one-way outlet valve V2118 and the disposable component outlet port 180 is 3.5-4.5 psig.One-way outlet valve V2 118, in the open position, contributes to thepositive pressure of the fluid in the bubble eliminator chamber 162versus the external vent area, causing venting of gas from the bubbleeliminator chamber 162 to the outside through the porous membrane 164.The result is that during the forward stroke of the disposable pistonpump assembly 140, bubbles are substantially eliminated from the fluidoccupying the bubble eliminator chamber 162.

FIG. 6B represents the fluid flow path during the prime stoke, duringwithdrawal of the plunger 146 and when reusable inlet valve 122 opens.The action of the plunger 146 causes depressurization of the fluid flowpath, such that fluid is drawn in from an external fluid source viareusable inlet valve 122. Fluid pressure in the vicinity of the pistonpump chamber 144 may be at −2.5 psig below the ambient atmosphericpressure. Depressurization of the fluid flow path causes the one-wayoutlet valves V1 114 and V2 118 (not shown) to close. Closure of one-wayoutlet valves V1 114 and V2 118 during the prime stroke is vital forcorrect function of the disposable bubble eliminator 160 and for correctfunction of the overall pump 100. Because one-way valve V1 114 islocated at the fluid entry side of the bubble eliminator chamber 162, itmechanically and hydraulically isolates the fluid in the bubbleeliminator chamber 162 from fluid depressurization caused by thewithdrawal action of the plunger 146. Thereby depressurization of thedisposable bubble elimination chamber 162 is substantially avoided whenone-way valve V1 114 closes. Consider if one-way valve V1 114 was notpresent at or near the bubble eliminator chamber 162 fluid entry point.Without isolation of the bubble eliminator chamber 162 from thedisposable piston pump assembly 140, depressurization of the bubbleeliminator chamber 162 fluid would occur during the prime stroke. Inthat case, the fluid pressure within the bubble eliminator chamber 162might equalize to the pressure of the surrounding atmosphere at the ventside of the porous membrane 164 and might fall below the pressure of thesurrounding atmosphere at the vent side of the porous membrane 164.These situations favor air being drawn into the disposable bubbleelimination chamber 162 from the outside via the porous membrane 164.This is undesirable. Excess air in the fluid flow path would compromisethe ability of pump 100 to achieve fluid delivery to the patient in acontrolled way. Fluid backflow towards the disposable component inletport 104 would also occur, which is not desired. With continued cyclingof the pump 100, there would be opportunity for gas bubbles to flow inthe direction of the patient. Further, if this were to occur, thereusable bubble detector 126 located between one-way valve V2 118 andthe patient side outlet 180 would be triggered, causing the pump to gointo a patient-safe mode of operation.

One-way outlet valve V2 118 is located in communication with the fluidexit side of the bubble eliminator chamber 162. When it closes duringthe prime stroke of the disposable piston pump assembly 140, itmechanically and hydraulically isolates the fluid in the bubbleeliminator chamber 162 from patient side disposable component outletport 180. Depressurization of the fluid present in the disposable bubbleeliminator 160 is thus minimized or prevented. The fluid pressureinternal to the bubble eliminator chamber 162 is maintained at or closeto 2.4 psig, as in FIG. 6B. Thus, during the prime stroke, the pressuredifferential across the porous membrane 164 is sufficient to causeventing of gas from solution to the outside atmosphere. The one-wayoutlet valve V2 118 plays an important role in managing the phenomenonof free flow. Free flow can occur when the vertical height of thedisposable bubble eliminator 160 lies above the vertical height of thetubing or conduit connecting to the patient, such that gravity-drivenflow of fluid in the direction of the patient outlet may occur. In theabsence of the one-way outlet valve V2 118, free flow would cause fluidpressure in the bubble eliminator chamber 162 to decrease leading tosiphoning of air into the bubble eliminator chamber 162 via the porousmembrane 164. Having the one-way outlet valve V2 118 in the closedposition minimizes this phenomenon. The presence of air intake into thebubble eliminator chamber 162 is undesirable. Excess air in the fluidflow path would compromise the ability of the pump 100 to achieve fluidflow and delivery to the patient in a controlled way. There would beopportunity for gas bubbles to flow in the direction of the patient.Further, if this occurred the reusable bubble detector 126 locatedbetween the one-way outlet valve V2 118 and the patient side outletwould be triggered, causing the pump to go into a patient-safe mode ofoperation.

The one-way outlet valves V1 114 and V2 118 (not shown) have dualfunction. Under pressure during the forward disposable piston pumpassembly 140 stroke, the one-way outlet valves V1 114 and V2118 open,but because of their orientation they only allow fluid to pass in thedirection of the patient outlet. As the fluid tries to reversedirection, the one-way outlet valves V1 114 and V2 118, being umbrellavalves, close and prevent any fluid from traveling towards the fluidinlet.

Disposable Bubble Eliminator 160 Design Details. The disposable bubbleeliminator 160 incorporates a low-cost air permeable, porous membrane164 that is capable of venting bubbles from the fluid as it is pumped.Expanded Polytetraflouroethylene (ePTFE) is commonly used in fluidseparation applications in medical devices due to its biocompatibilityand ability to resist wetting out. Air is allowed to permeate throughthe filter via a positive pressure differential between the two sides ofthe porous membrane 164. This means that the fluid side must alwaysremain at a higher pressure than the atmosphere, otherwise it ispossible to pull air into the fluid stream from outside the disposablebubble eliminator 160. Therefore, the vent needs to be strategicallyplaced in the flow such that positive pressure conditions can bemaintained at all times. By placing the ePTFE vent on the patient sideof the disposable piston pump assembly 140, the fluid pressure ismaintained to be at least atmospheric throughout operation. One-wayoutlet valve V1 114 (not shown) prevents the prime stroke from pulling avacuum on the vent downstream, also known as backflow. The one-wayoutlet valve V2 118 (not shown), with a suitably high cracking pressure,ensures that no air is pulled into the line by syphoning when the needleis below the disposable bubble eliminator 160. The latter scenario isknown as free-flow.

Expanded PTFE membranes come in many different blends that vary in airpermeability rates (ft³/min/ft²), thickness, pore size (m), burstpressure, and hydrophobicity. Increased air permeability is an obviousadvantage for bubble elimination at high flow rates, but it typicallycomes at the expense of burst pressure. A sufficiently breathablemembrane must also allow several factors of safety for nominal andoff-nominal pressure scenarios. As fluid pressure increases, it istypical for the membrane to deform outward into a dome shape. This notonly poses a strength-of-materials risk but changes the venting criteriavital to effective air removal, as discussed herein. To mitigate this, arigid mesh backing 166 is secured on the outside of the ePTFE membrane,which permits air breathability while maintaining the flat shape desiredfor venting.

Several factors determine the efficacy of the porous membrane 164 duringpumping: bubble length, travel time, velocity, and pressure difference.To start, the pump 100 has a large range of flow rates at which it mustfacilitate this safety feature of removing gas from the fluid. Theseflow rates are accentuated by the duty cycle of the priming and pumpingstrokes: at an average flow rate of 500 mL/hr, the instantaneous flowrate in the fluid may be closer to 1,000 mL/hr. This translates to avery brief time that a fluid particle has in contact with the porousmembrane 164, called residence time. The air bubble must have asufficient residence time to allow mass transport to occur. Masstransport is the movement of air molecules through the pores of theporous membrane 164 caused by the pressure differential across theePTFE. There is an inherent time required to pass a given number ofmolecules through the porous membrane 164, a value dictated by thematerial permeability and fluid pressure. It is desirable to maximizethe bubble's exposure on the porous membrane 164 to allow all airmolecules enough time to escape. Residence time can be controlled byslowing the velocity of the fluid through deliberate geometric design ofthe flow path: when increasing the travel length l for a given velocity,the residence must increase. Additionally, by expanding the fluidcross-sectional area to a critical dimension (thickness and width A),the velocity may be reduced to an effective value relative to othergeometries for a given flow rate {dot over (m)} as understood byEquation 1:

$v = {\frac{l}{t} = \frac{\overset{.}{m}}{A}}$

A liquid-gas interface creates a contact angle between the porousmembrane 164 and the bubble boundary. As the bubble velocity increases,this contact angle approaches zero for which no triple point (air,membrane, liquid) exists and a stable film is formed. The film inhibitsthe direct exposure of air molecules to the porous membrane 164. Thebubble velocity then must be less than a critical value at which thefilm forms to prevent any mass transfer from occurring. This criticalvelocity is governed by Equation 2:

$v_{c} = {\frac{1}{9\sqrt{3}}\frac{\gamma/\mu}{20}\theta_{E}^{3}}$

In Equation 1, γ is the surface tension between gas and liquid, μ is theviscosity of the gas, and θ_(E) is the contact angle of the bubble onthe porous membrane 164 surface.

Regarding cross-sectional area, there is an optimal value to whichporous membrane 164 performance and pump 100 capability must be found.It is favorable to spread the bubble as wide and thin as possible so asto expose a greater area of air to the porous membrane 164 and thus ventin a shorter amount of time. One obvious limitation is disposable bubbleeliminator 160 space. However, perhaps more important is the effect ofpressure losses through the disposable bubble eliminator chamber 162. Avariation in flow field thickness impacts the pressure by a power oftwo. Increased pressure during the infusion stroke translates to ahigher effective power required by the pump actuation mechanisms. Thus,an improperly designed bubble vent will cost the system valuable batterylife to perform its normal function, or otherwise not effectivelydisperse a bubble to an area conducive for complete mass transport. Thedisposable bubble eliminator 160 design presented by the presentinvention provides a unique solution to the problems identified above.

The design of the disposable bubble eliminator 160 was iterated manytimes before reaching a suitable configuration for all fluid types.Initial proof of concept designs, which showed effective bubble removalin water, had to be greatly re-evaluated once testing with whole bloodand blood component samples such as packed red blood cells. The complexmulti-component makeup, along with altered fluid characteristics, meantthat bubbles could not effectively be removed even at low flow rates.Additionally, blood cell damage (hemolysis) must be considered whendesigning the disposable bubble eliminator 160. Methods that causeextreme shear stress or have excessively rough surface finishes couldcause patient harm, so careful testing and analysis must be performedwhen designing this feature.

The functioning design must minimize the velocity of the fluid acrossthe membrane, thus increasing its residence time to vent all air.Velocity is a function of flow rate and the cross-sectional area of theflow field: increasing the area decreases the velocity at a given flowrate. However, the width will be limited by the overall sizerequirements of the disposable bubble eliminator 160 and the thicknesswill be limited by pressure drop as the fluid tries to pass through it.The path length may also be varied to increase residence time but mustalso consider size and pressure constraints. A membrane exhibitingsuperior air permeability rates could reduce the overall size requiredto vent the bubble, but its pore size, burst pressure, andbiocompatibility will determine if its selection is appropriate in thisapplication.

The general design parameters of the disposable bubble eliminator 160are shown in Table 1. These outline the variables that are combined tomake for an effective disposable bubble eliminator 160. The table servesas a non-limiting example for a functional embodiment of a disposablebubble eliminator 160 as it is used with the pump 100.

TABLE 1 of Variables for Disposable Bubble Eliminator 160 # VariableRange Requirements 1 Flow Rate 0.1-999 mL/hr System RequirementThreshold 2 Bubble Volume 50-100 uL System Requirement Threshold 3Compact Size 0.005-0.15 in³ System Requirement Threshold 4 Pressure0.1-10 PSIG Atmospheric < P < Burst Pressure 5 Membrane Air 0.20-0.45ft³/min/ft² @ Permeability should not drastically Permeability 125 Paminimize burst pressure rating 6 Path Length 0.6-0.7 in L >> H 7 PathWidth 0.85-1.0 in Maximize bubble area 8 Flow Field 0.004-0.007 inPressure drop should not be Thickness excessive 9 Velocity 5-15 in/s V <V_(Critical) 10 Residence Time 0.06-0.17 s T_(Residence) < Time requiredto vent all air

To reach a suitable design of the disposable bubble eliminator 160, aspecific set of tests were conducted which introduced regulated bubblesinto a controlled stream of fluid, which was directed to flow to thebubble eliminator chamber test subject (with dimensions varied asindicated below). A syringe pump was used to control the rate of liquidflow. A 3 mL syringe was connected by an in-line three-way luer-lockvalve upstream of the test subject. At the time of test, the valve wasopened to allow a 0.2-1.0 mL air bubble into the free stream from thesyringe. A 7 mL syringe downstream of the test piece collected allliquid and air pumped through the bubble eliminator chamber 162, and theremaining air bubble was measured and compared against the input volume.Each disposable bubble eliminator 160 design iteration was recorded topass or fail based on its ability to remove over 50% of air from fluidat all three distinct flow rates: 50 mL/hr, 1,000 mL/hr, and 2,000mL/hr.

FIGS. 7A-7G depict the bubble eliminator chamber 162 in one embodiment.In FIG. 7A, length l is defined by the distance from the center pointsof the inlet and outlet. Width w is defined by the distance from eitherwall perpendicular to the mean flow direction. Thickness t is defined bythe spacer 168 height as shown. It is assumed that the porous membrane164 (not sown) exists on the top plane of the depicted bubble eliminatorchamber 162, forming a hydraulic seal around the rectangular housing.The fluid inlet is the left-hand cylindrical borehole which isperpendicular to the plane of the bubble eliminator chamber 162. Thefluid outlet is the right-hand cylindrical borehole which isperpendicular to the plane of the bubble eliminator chamber 162. FIG. 7Bdepicts the approximate flow lines for this embodiment by arrows. Alarge distribution of flow passes through the direct line between theinlet and outlet, while slower flow is pushed toward the periphery ofthe bubble eliminator chamber 162. Computational fluid dynamic analysisshows that the highest pressure exists nearest the inlet port andgradually decreases as flow moves to the outlet port.

FIG. 7C depicts a bubble 700 of approximately 500 uL in volume beginningto enter the bubble eliminator chamber 162 through the inlet port. Thefluid is flowing at the highest expected flow rate of 2,000 mL/hr ascontrolled by a syringe pump. Not all of the bubble has entered thebubble eliminator chamber 162. A relatively circular distribution of thebubble begins to form on the surface of the ePTFE.

FIG. 7D depicts the bubble 700 of approximately 500 uL in volumecontinuing to fill the bubble eliminator chamber 162. It expands in areaas it enters the bubble eliminator chamber 162, but it may or may nottake the shape depicted in FIG. 7D; the shape shown is exemplary andnon-limiting. A significant portion of the air within the bubble is indirect contact with the ePTFE membrane and is vented with a rate definedby the air permeability and instantaneous local pressure in the bubbleeliminator chamber 162. No stable film exists between the bubble and themembrane due to the velocity with which the bubble moves across themembrane.

FIG. 7E depicts the bubble 700 beginning to lose volume within thebubble eliminator chamber 162. As it does so, the leading edges of thebubble reverse in on itself while more air continues to enter form theinlet port. It is common for smaller bubbles (less than 50 μL) to formas the parent bubble collapses, however it may or may not take the shapedepicted in FIG. 7E; the shape shown is exemplary and non-limiting.

FIG. 7F depicts the bubble 700 continuing to lose volume within thebubble eliminator chamber 162. Smaller bubbles have broken off from theoriginal bubble but continue to vent.

FIG. 7G depicts the last remaining air bubbles of bubble 700 within thebubble eliminator chamber 162. At this point, the air in the fluid flowis significantly reduced in volume. Bubbles of very small size (lessthan 20 μL) commonly move through the remainder of the bubble eliminatorchamber 162 without being eliminated. This is due to the ratio of bubblevolume to its dispersed area and the contact angle formed with a morespherical bubble as opposed to a flattened bubble.

FIGS. 7C-7G depict the disposable bubble eliminator 160 effectivelyperforming in one embodiment, with the bubble progressively becomingsmaller as the bubble's air passes out through the porous membrane 164(not shown). The test case shown here would be considered a passingcriterion as it properly removed >50% of a bubble of 500 μL in volumefrom a fluid passing at 2,000 mL/hr. The fluid flow path sufficientlycontrolled the bubble to a velocity in which no stable film formedbetween the air boundary and the porous membrane 164. The fluid flowpath sufficiently dispersed the bubble to an area conducive to vent theair quickly. The fluid flow path was long enough to allow theelimination of the air before it escaped the bubble eliminator chamber162. The chosen porous membrane 164 sufficiently passed air acrossitself under the given pressure without harm or risk of bursting.

FIGS. 8A-8K and Table 2 illustrate results of a study to investigatevarious bubble venting specifications, Examples 1-11. FIGS. 8A-8K eachdepict top views and side views of the bubble eliminator chamber 162 andbubble 800. Porous membrane 164 is also shown.

TABLE 2 Results of a study to investigate various bubble ventingspecifications for Examples 1-11. FIG. Example Design ObservationPass/Fail FIG. 8A 1 Path length 0.6 in No failures: Pass (blood) Pathwidth 0.85 in bubble Flow Field thickness 0.004 in removed >90% Velocity9.9 in/sec Residence time 0.6 sec FIG. 8B 2 Path length 0.5 in Nofailures: Pass (blood) Path width 1.0 in bubble Flow Field thickness0.004 in removed >90% Velocity 8.4 in/sec Residence time 0.6 sec FIG. 8C3 Path length 0.6 in No failures: Pass (blood) Path width 0.85 in bubbleFlow Field thickness 0.008 in removed >90% Velocity 4.9 in/sec Residencetime 0.12 sec FIG. 8D 4 Path length 0.6 in No failures: Pass (saline)Path width 0.85 in bubble Flow Field thickness 0.004 in removed >90%Velocity 9.9 in/sec Residence time 0.06 sec FIG. 8E 5 Path length 0.6 inNo failures: Pass (saline) Path width 0.85 in bubble Flow Fieldthickness 0.008 in removed >90% Velocity 4.9 in/sec Residence time 0.12sec FIG. 8F 6 Path length 0.6 in No failures: Pass (saline) Path width0.85 in bubble Flow Field thickness 0.008 in removed >90% Velocity 4.9in/sec Residence time 0.12 sec FIG. 8G 7 Path length 0.5 in Bubble Fail(blood) Path width 0.5 in breakthrough: Flow Field thickness 0.004 ininsufficient Velocity 16.9 in/sec contact Residence time 0.03 sec areaand residence time FIG. 8H 8 Path length 1.0 in Bubble Fail (blood) Pathwidth 0.42 in breakthrough: Flow Field thickness 0.004 in insufficientVelocity 19.7 in/sec contact area Residence time 0.03 sec and residencetime FIG. 8I 9 Path length 1.0 in Bubble Fail (blood) Path width 0.42 inbreakthrough: Flow Field thickness 0.008 in insufficient Velocity 9.8in/sec contact area Residence time 0.06 sec and residence time FIG. 8J10 Path length 1.2 in Bubble Fail (blood) Path width 0.25 inbreakthrough: Flow Field thickness 0.05 in insufficient Velocity 2.7in/sec contact area and residence Residence time 0.44 sec time FIG. 8K11 Path length 0.6 in Excessive Fail (blood) Path width 1.5 in pressuredrop; Flow Field thickness 0.002 in pump loses Velocity 11.1 in/secperformance Residence time 0.05 sec

These values make assumptions about the fluid's viscosity, Reynoldsnumber, and flow rate. In each example, the disposable piston pumpassembly 140 specifications were: stroke volume=0.7 mL; piston chamber144 ID 0.59 in; stroke length 0.156 in. The spring 152 of the disposablepiston pump assembly 140 was of stainless steel (Century Spring): freelength 1.16 in; compressed length 0.35 in; ID 0.695 in; stiffness 1.3lb/in priming force 1-0.4 lb; infusing force 0.4-1.6 lb. The plunger 146was a loss of resistance (LOR) lip seal type (Portex). The porousmembrane 164 material was ePTFE (Sterlitech): thickness=0.008-0012 in.Repeated forward motion of the plunger 146 was achieved using an Admetmechanical actuator.

Examples 1 and 2 (FIGS. 8A and 8B, respectively) were conducted usingblood. Bubble elimination was achieved successfully. These examplesspecify a successful design in terms of the disposable bubble eliminatorchamber 162 dimensions relative to flow velocity, for adequate bubblecontact with the porous membrane 164 leading to bubble elimination.Confinement of the bubble 800 in the bubble eliminator chamber 162 isimportant. The flow field thickness was 0.004 in. We observed that theellipse of the bubble at the liquid membrane interface was highlyoblate, indicative of a “flattened” bubble geometry, favorable to rapidgas exchange.

Example 3 (FIG. 8C) was less successful than Examples 1 and 2. Thedesign was marginal. A lower velocity and longer residence time shouldbenefit gas bubble venting but the expected benefit did not occur. Weobserved that the ellipse of the bubble 800 at the liquid membraneinterface was more circular, less oblate, indicating the bubble 800 wasless confined and closer to spherical geometry in the channel than inExamples 1 and 2. This design with its thicker flow field thickness(0.008 in vs 0.004 in) is less favorable to venting.

Examples 4-6 (FIGS. 8D-8F, respectively) involved substitution of bloodfor saline solution. The low viscous nature of Ringer's solutioncompared to blood improved the performance of the vent, resulting inthree successful trials.

Example 7 (FIG. 8G) was an ineffective design when tested with blood.The high flow velocity and short residence time was detrimental tobubble elimination. We observed that the ellipse of the bubble 800 atthe liquid membrane interface tended to be circular rather than oblate(flattened) limiting the amount of bubble surface area was in contactwith the porous membrane 164. Therefore, despite possibly having nostable film developed between the air and the membrane, the bubble 800did not have the time required to transfer air across the porousmembrane 164.

Example 8 (FIG. 8H) was an ineffective design when tested with blood.The high flow velocity and short residence time was detrimental tobubble elimination. The velocity exceeded the critical value for which astable film is formed between the air and the membrane. Despite theincreased travel length, the film prevented the transfer of air acrossthe permeable membrane, thus allowing all of the bubble 800 to escapethe bubble eliminator chamber 162.

Example 9 (FIG. 8I) was an ineffective design when tested with blood. Weobserved that the ellipse of the bubble at the liquid membrane interfacetended to be circular rather than oblate (flattened) which limited theamount of bubble surface area was in contact with the porous membrane164. The flow path width was too narrow to effectively disperse thebubble for maximum contact with the porous membrane 164.

Example 10 (FIG. 8J) was an ineffective design due to its flow fieldthickness of 0.05 in. While the velocity was low enough to prevent theformation of a stable film between the air and membrane, the circularcross-section of the bubble resulted in a very low contact area to themembrane. Thus, air could not escape the bubble eliminator chamber 162.

Example 11 (FIG. 8K) was an ineffective design due to the excessivepressure drop experienced by the fluid. Despite the bubble beingsignificantly dispersed and having sufficient velocity for masstransfer, the pressure losses due to the extremely narrow flow chamberput undue stress on the pump 100. Increased pressure drop in the bubbleeliminator chamber 162 is undesirable because it translates to increasedpower consumption by the pump.

FIGS. 9A-9D schematically depict Examples 12-15, representing additionalconfigurations tested. Each example shows the effect of modified valveconfigurations on the pump's function. In each example, thespecifications of the disposable piston pump assembly 140 were: strokevolume=0.7 mL; piston chamber 144 ID 0.59 in; stroke length 0.156 in.The spring 152 was of stainless steel (Century Spring): free length 1.16in; compressed length 0.35 in; ID 0.695 in; stiffness 1.3 lb/in primingforce 1-0.4 lb; infusing force 0.4-1.6 lb. The plunger 146 was a loss ofresistance (LOR) lip seal type (Portex). The porous membrane 164material was ePTFE (Sterlitech): thickness=0.008-0.0012 in.

Example 12 (FIG. 9A). This is a pump configuration omitting the one-wayoutlet valves V1 114 and V2 118 from the fluid flow path. A pump 100 ofthis design was set to operate at a flow rate of 500 mL per hour. Thefluid was whole blood. During the priming stroke, when valve 122 wasopen, significant air intake into the fluid flow line occurred caused bydepressurization of the bubble eliminator chamber 162. Back flow wasobserved. Pump 100 operation became ineffective after a few cycles.

Example 13 (FIG. 9B). Fluid flow path includes one-way outlet valve V1114 located at or near the bubble eliminator chamber 162 fluid entrypoint and is oriented to allow flow only in the direction of thedisposable component outlet port 180 (not shown). There is no one-wayoutlet valve V2 118 in this configuration. The pump 100 was set tooperate at 500 mL per hour flow rate using whole blood. Closure ofone-way outlet valve V1 114 during disposable piston pump assembly 140priming isolates the bubble eliminator chamber 162 from thedepressurization effect due to retraction of the plunger 146. However,the bubble eliminator chamber 162 is not isolated from the patientdisposable component outlet port 180 (not shown). Lower conduit heightversus the height of the bubble eliminator chamber 162 caused fluid freeflow in the direction of the disposable component outlet port 180.Concurrently, air siphoned into the bubble eliminator chamber 162 fromthe outside atmosphere via the gas permeable porous membrane 164. Pump100 operation was ineffective after a few cycles due to excess air inthe fluid flow path and inability to control the rate of fluid flow tothe disposable component outlet port 180.

Example 14 (FIG. 9C). Fluid flow path includes the one-way outlet valveV2 118 in proximity to the fluid exit point of the disposable bubbleeliminator 160, which is oriented to allow flow only in the direction ofthe disposable component outlet port 180 (not shown). There is noone-way outlet valve V1 114 in this example. The pump 100 was operatedat 500 mL per hour flow rate using whole blood. Closure of the one-wayoutlet valve V2 118 during the disposable piston pump assembly 140 primestroke isolated the bubble eliminator chamber 162 to prevent fluid freeflow in the direction of the disposable component outlet port 180.However, the bubble eliminator chamber 162 is not isolated from thedepressurization effect due to the retraction of the pump plunger 146.When the disposable piston pump assembly 140 was operated, air siphonedinto the flow system across the gas permeable porous membrane 164 andfluid backflow was observed occurring from the bubble eliminator chamber162 towards the disposable piston pump assembly 140. Pump 100 operationwas ineffective after 10 cycles due to excess air in the fluid flow pathand inability to control the rate of fluid flow to the disposablecomponent outlet port 180.

Example 15 (FIG. 9D). The fluid flow path includes one-way outlet valvesV1 114 and V2 118 arranged and oriented as in FIGS. 1 and 2 . The pump100 was operated at 500 ml per hour using whole blood. Bubbleelimination was effective. No air siphoned into the bubble eliminatorchamber 162 even after extended use. The desired flow rate was constantat exactly at 500 mL/hr over hundreds of duty cycles of the pump.

FIG. 10 shows a flowchart for a method embodiment of the presentinvention. Method 1000 includes in block 1005 providing a disposablepump component including a disposable component inlet port coupled to afirst disposable conduit in fluid communication with a fluid mediumsource, wherein the first disposable conduit includes a disposablepiston pump assembly and a disposable bubble eliminator, and the firstdisposable conduit is in fluid communication with a disposable componentoutlet port, wherein the disposable bubble eliminator is in fluidcommunication with a lumen of the first disposable conduit and isoperable to reduce a gas content of a fluid medium, and wherein thedisposable piston pump assembly is operable to pump the fluid mediumfrom the disposable component inlet port, through the first disposableconduit and the disposable bubble eliminator, to the disposablecomponent outlet port. Block 1010 includes connecting the disposablecomponent to a reusable component including a reusable movable stageoperable to compress the disposable piston pump assembly; and a reusablemechanical actuator operable to drive the movable stage.

FIG. 11 shows a flowchart for another method embodiment of the presentinvention. Block 1105 of method 1100 of pumping a fluid medium includesreceiving the fluid medium from a fluid medium source into a conduit.Block 1110 includes drawing the fluid medium into a disposable pistonpump assembly in the conduit, the conduit further comprising adisposable bubble eliminator operable to vent gas from the fluid mediumwithin the disposable bubble eliminator. Flowing the fluid mediumthrough a disposable flow meter is included in block 1115. Measuring aflow rate of the fluid medium is included in block 1120. Block 1125includes discharging the fluid medium into a reusable bubble detector.Block 1130 includes detecting residual gas in the fluid medium. Block1135 includes discharging the fluid medium from the reusable bubbledetector if less than a preselected amount of gas is detected.

The pump 100 may be included in a kit that also includes one or moreother items commonly used when infusing liquids to a patient.

Those skilled in the art of infusion pumps will recognize that the pump100, the methods 1000 and 1100 and the kit disclosed herein answer theneed for an infusion pump that reduces or removes gases from fluids tobe infused, is less costly than using and cleaning reusable pumps,ensures correct direction of fluid flow, prevents uncontrolled flow offluid to be infused, and controls the rate of flow of fluid that isbeing infused.

It will be understood that particular embodiments described herein areshown by way of illustration and not as limitations of the invention.The principal features of this invention can be employed in variousembodiments without departing from the scope of the invention. Thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, numerous equivalents to the specificprocedures described herein. Such equivalents are considered to bewithin the scope of this invention and are covered by the claims.

All publications and patent applications mentioned in the specificationare indicative of the level of skill of those skilled in the art towhich this invention pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.” The use of the term “or” in the claims isused to mean “and/or” unless explicitly indicated to refer toalternatives only or the alternatives are mutually exclusive, althoughthe disclosure supports a definition that refers to only alternativesand “and/or.” Throughout this application, the term “about” is used toindicate that a value includes the inherent variation of error for thedevice, the method being employed to determine the value, or thevariation that exists among the study subjects.

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps. In embodiments of any of the compositions andmethods provided herein, “comprising” may be replaced with “consistingessentially of” or “consisting of” As used herein, the phrase“consisting essentially of” requires the specified integer(s) or stepsas well as those that do not materially affect the character or functionof the claimed invention. As used herein, the term “consisting” is usedto indicate the presence of the recited integer (e.g., a feature, anelement, a characteristic, a property, a method/process step, or alimitation) or group of integers (e.g., feature(s), element(s),characteristic(s), property(ies), method/process(s) steps, orlimitation(s)) only.

The term “or combinations thereof” as used herein refers to allpermutations and combinations of the listed items preceding the term.For example, “A, B, C, or combinations thereof” is intended to includeat least one of: A, B, C, AB, AC, BC, or ABC, and if order is importantin a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.Continuing with this example, expressly included are combinations thatcontain repeats of one or more item or term, such as BB, AAA, AB, BBC,AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan willunderstand that typically there is no limit on the number of items orterms in any combination, unless otherwise apparent from the context.

As used herein, words of approximation such as, without limitation,“about,” “substantial” or “substantially” refers to a condition thatwhen so modified is understood to not necessarily be absolute or perfectbut would be considered close enough to those of ordinary skill in theart to warrant designating the condition as being present. The extent towhich the description may vary will depend on how great a change can beinstituted and still have one of ordinary skill in the art recognize themodified feature as still having the required characteristics andcapabilities of the unmodified feature. In general, but subject to thepreceding discussion, a numerical value herein that is modified by aword of approximation such as “about” may vary from the stated value byat least ±1, 2, 3, 4, 5, 6, 7, 10, 12 or 15%.

All of the devices and/or methods disclosed and claimed herein can bemade and executed without undue experimentation in light of the presentdisclosure. While the devices and/or methods of this invention have beendescribed in terms of particular embodiments, it will be apparent tothose of skill in the art that variations may be applied to thecompositions and/or methods and in the steps or in the sequence of stepsof the method described herein without departing from the concept,spirit and scope of the invention. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope, and concept of the invention as defined by theappended claims.

Furthermore, no limitations are intended to the details of constructionor design herein shown, other than as described in the claims below. Itis therefore evident that the particular embodiments disclosed above maybe altered or modified and all such variations are considered within thescope and spirit of the disclosure. Accordingly, the protection soughtherein is as set forth in the claims below.

Modifications, additions, or omissions may be made to the systems andapparatuses described herein without departing from the scope of theinvention. The components of the systems and apparatuses may beintegrated or separated. Moreover, the operations of the systems andapparatuses may be performed by more, fewer, or other components. Themethods may include more, fewer, or other steps. Additionally, steps maybe performed in any suitable order.

To aid the Patent Office, and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims to invoke 35U.S.C. § 112(f) as it exists on the date of filing hereof unless thewords “means for” or “step for” are explicitly used in the particularclaim.

What is claimed is: 1.-23. (canceled)
 24. A method of pumping a fluidcomprising: providing a pump comprising: a disposable componentcomprising: a disposable component inlet port coupled to a firstdisposable conduit in fluid communication with a fluid medium source,wherein the first disposable conduit comprises a disposable piston pumpassembly and a disposable bubble eliminator, and the first disposableconduit is in fluid communication with a disposable component outletport, wherein the disposable bubble eliminator is in fluid communicationwith a lumen of the first disposable conduit and is operable to reduce agas content of a fluid medium; wherein the disposable piston pumpassembly comprises a plunger in direct contact with the fluid medium,and wherein the disposable piston pump assembly is operable to pump thefluid medium from the disposable component inlet port, through the firstdisposable conduit and the disposable bubble eliminator, to thedisposable component outlet port; a first one-way outlet valve disposedin the first disposable conduit between the piston assembly and thedisposable bubble eliminator and operable to prevent the fluid mediumfrom flowing from the disposable bubble eliminator to the disposablepiston pump assembly; a second disposable conduit that places thedisposable bubble eliminator in fluid communication with a disposableflow meter; a second one-way outlet valve disposed in the seconddisposable conduit between the disposable bubble eliminator and thedisposable flow meter and operable to prevent the fluid medium fromflowing from the disposable flow meter to the disposable bubbleeliminator; and a reusable component comprising: a reusable movablestage operable to compress the disposable piston pump assembly; areusable mechanical actuator operable to drive the reusable movablestage; a reusable reception tunnel configured to receive at least aportion of the first disposable conduit; a reusable inlet valve operableto close the first disposable conduit when the at least a portion of thefirst disposable conduit is disposed in the reusable reception tunnel; areusable flow meter connector operable to connect to the disposable flowmeter and to convey data from the disposable flow meter; and a reusablebubble detector; connecting the disposable component and the reusablecomponent; receiving the fluid medium from the fluid medium source intothe first disposable conduit; drawing the fluid medium into thedisposable piston pump assembly of the first disposable conduit; flowingthe fluid medium through the disposable flow meter; measuring a flowrate of the fluid medium; discharging the fluid medium into the reusablebubble detector; and discharging the fluid medium from the reusablebubble detector if less than a preselected amount of gas is detected.25. The method of claim 24, wherein the disposable piston pump assemblyfurther comprises: a piston barrel comprising: a pump chamber in fluidcommunication with the first disposable conduit; a plunger slidablydisposed within the piston barrel below the pump chamber; a piston rodattached to the plunger opposite the pump chamber; a spring cap attachedto the piston rod; and a spring disposed around an exterior of thepiston barrel and attached at an upper end of the spring to the exteriorof the piston barrel and at a lower end of the spring to the spring cap,wherein the spring is disposed to store energy when the plunger, thepiston rod, and the spring cap are moved from a lower end of the pistonbarrel and is disposed not to store energy when the plunger is at thelower end of the pump chamber; wherein the reusable movable stage isdisposed to move the plunger into the pump chamber and the spring isdisposed to move the plunger out of the pump chamber.
 26. The method ofclaim 24, wherein the disposable bubble eliminator is in fluidcommunication with the disposable piston pump assembly and thedisposable flow meter and comprises a vent through which gas in thefluid medium may escape the disposable bubble eliminator to theatmosphere when pressure higher than atmospheric pressure is maintainedin the disposable bubble eliminator.
 27. The method of claim 24, whereinthe disposable component further comprises a disposable positionmeasurement device to detect an alignment of the disposable componentwith the reusable component when assembled together; and furthercomprising detecting an alignment of the disposable component with thereusable component when assembled together.
 28. The method of claim 24,wherein the reusable bubble detector comprises: a reusable bubbledetector conduit in fluid communication with the disposable componentoutlet port when the disposable component and the reusable component areassembled together; and a reusable ultrasonic sensor to detect gas inthe fluid medium, disposed outside the reusable bubble detector conduit.29. The method of claim 24, further comprising supplying electricalpower from an internal electric battery or an external electrical powersource.
 30. The method of claim 24, further comprising managingelectrical power with an internal power management system.
 31. Themethod of claim 24, further comprising managing electrical power with anexternal power management system.
 32. The method of claim 24, whereinthe pump comprises an integral screen interface.
 33. The method of claim24, wherein the pump comprises an external screen interface.
 34. A pumpcomprising: a disposable component comprising: a disposable componentinlet port coupled to a first disposable conduit in fluid communicationwith a fluid medium source, wherein the first disposable conduitcomprises a disposable piston pump assembly and a disposable bubbleeliminator, and the first disposable conduit is in fluid communicationwith a disposable component outlet port, wherein the disposable bubbleeliminator is in fluid communication with a lumen of the firstdisposable conduit and is operable to reduce a gas content of a fluidmedium; wherein the disposable piston pump assembly is operable to pumpthe fluid medium from the disposable component inlet port, through thefirst disposable conduit and the disposable bubble eliminator, to thedisposable component outlet port; and a reusable component comprising: areusable movable stage operable to compress the disposable piston pumpassembly; and a reusable mechanical actuator operable to drive themovable stage.
 35. A pump kit comprising: a disposable componentcomprising: a disposable component inlet port coupled to a firstdisposable conduit in fluid communication with a fluid medium source,wherein the first disposable conduit comprises a disposable piston pumpassembly and a disposable bubble eliminator, and the first disposableconduit is in fluid communication with a disposable component outletport, wherein the disposable bubble eliminator is in fluid communicationwith a lumen of the first disposable conduit and is operable to reduce agas content of a fluid medium; wherein the disposable piston pumpassembly is operable to pump the fluid medium from the disposablecomponent inlet port, through the first disposable conduit and thedisposable bubble eliminator, to the disposable component outlet port;and a reusable component comprising: a reusable movable stage operableto compress the disposable piston pump assembly; and a reusablemechanical actuator operable to drive the movable stage.